Clear Array of Duplicates and empty values
const arr = [‘Laurence’,’Jack’,’Jane’,”,,,,’Sam’,’Laurence’,’Jack’,’Jane’,”,null,false,undefined,0,’Sam’];
console.log(arr);
const arr1 = [… new Set(arr)];
console.log(arr1);
const arr2 = arr.filter(Boolean);
console.log(arr2);
const arr3 = [… new Set(arr.filter(Boolean))];
console.log(arr3);
How to loop through an array
const arr = [‘Laurence’,’Linda’,’Joe’,’Jane’];
console.log(arr);
console.log(‘****FOR’);
for(let i=0;i<arr.length;i++){
console.log(arr[i]);
}
console.log(‘****WHILE’);
let i=0;
while(i<arr.length){
console.log(arr[i]);
i++;
}
console.log(‘****ForEach’);
arr.forEach((item,index,array)=>{
console.log(item);
})
console.log(‘****MAP’);
const arr1 = arr.map((item,index)=>{
console.log(item);
return `${index} ${item}`;
})
console.log(‘****Filter’);
const arr2 = arr.filter((item)=>{
console.log(item);
return item;
});
console.log(arr2);
Array Updating adding and removing array items
const arr = [‘Laurence’,’Next’];
arr.push(‘End Push’); //adds to end
const val1 = arr.shift(); //removes first
const val2 = arr.pop(); //removes last
arr.unshift(val1); // adds to start
console.log(val1);
console.log(val2);
console.log(arr);
const str1 = arr.toString();
console.log(str1);
const str2 = arr.join(‘*-*’);
console.log(str2);
JavaScript Map Method for Arrays new array
const arr = [‘Laurence’,4,545,false,’Test’];
const arr2 = arr;
arr2.push(‘NEW’);
console.log(arr);
const arr1 = arr.map((item,index,array)=>{
const temp = `${index} ${item}`;
return temp;
})
arr2.push(‘NEW’);
console.log(arr1);
const arr3 = [3,54,62,4334,1232,444];
const arr4 = arr3.map(val => val*2);
console.log(arr4);
const arr5 = arr3.map(callback1);
console.log(arr5);
function callback1(item){
console.log(item);
return item*2;
}
const arr6 = [{first:’Laurence’,last:’Svekis’},{first:’John’,last:’Smith’},{first:’Sam’,last:’Jones’}]
console.log(arr6);
const arr7 = arr6.map(({first,last})=>{
//console.log(first,last);
//return `${first} ${last}`;
return {fullName:`${first} ${last}`}
})
console.log(arr7);
const arr8 = arr6.map(({first,last})=> ({full:`${first} ${last}`}));
console.log(arr8);
How to concat arrays and duplicate an array
const arr1 = [‘Laurence’,’Svekis’];
const arr2 = [1,2,3,4,5];
const arr3 = arr1.concat(arr2);
console.log(arr3);
const arr4 = arr1.concat(arr2,[‘new1′,’new2’]);
console.log(arr4);
const arr5 = arr2.concat(arr2,arr2);
console.log(arr5);
const arr6 = arr1;
arr6.push(‘END’);
const arr7 = arr1.concat();
arr6.push(‘more’);
console.log(arr7);
console.log(arr1);
console.log(arr6);
Array iterator entries using entries and looping items
const arr1 = [‘Laurence’,’Svekis’,100];
const adder = arr1.entries();
console.log(adder);
//console.log(adder.next());
//console.log(adder.next().value);
for(let item of adder){
console.log(item[1]);
}
const adder1 = arr1.entries();
let val = adder1.next();
while(val.value){
console.log(val.value[1]);
val = adder1.next();
}
Array Filter Method Example for JavaScript Arrays
const arr = [‘Svekis’,’Laurence’,’test’,’new’,5,23,54,5,1213343];
const arr1 = arr.filter(val => val.length >= 4);
console.log(arr1);
const arr2 = arr.filter(checker);
console.log(arr2);
function checker(item,index,array){
//console.log(item);
/// console.log(index);
//console.log(array);
return index >=2;
}
const arr3 = arr.filter((item,index)=>{
//console.log(typeof(item) );
return typeof(item) == ‘string’;
});
console.log(arr3);
arr.push(null);
arr.push(false);
console.log(arr);
const arr4 = arr.filter(Boolean);
console.log(arr4);
const arr5 = arr.filter((str)=>{
if(typeof(str)==’string’){
const first = str[0].toUpperCase();
return first === str[0];
}
})
console.log(arr5);
Array includes Method and index methods JavaScript coding Example
const arr = [‘Laurence’,’Svekis’,’Svekis’,100,’Svekis’,1000];
const boo1 = arr.includes(‘Svekis’);
console.log(boo1);
const boo2 = arr.includes(‘test’);
console.log(boo2);
const ind1 = arr.indexOf(‘Svekis’);
console.log(ind1);
const ind2 = arr.indexOf(‘test’);
console.log(ind2);
const lind1 = arr.lastIndexOf(‘Svekis’);
console.log(lind1);
const lind2 = arr.lastIndexOf(‘test’);
console.log(lind2);
const find1 = arr.findIndex(call1);
console.log(find1);
const find2 = arr.findIndex(call2);
console.log(find2);
function call1(item){
//console.log(item);
if(item === ‘Svekis’ ){
return item;
}
}
function call2(item){
if(typeof(item)==’number’){
return item;
}
}
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